Bow-Type Throwing Tool

ABSTRACT

A bow-type throwing tool includes a central body, a nocking string for an arrow, and elastic energy storage mechanism operated by the traction of the string. The elastic energy storage mechanism includes: two opposed primary levers connected with hinging to the central body, the nocking string being constrained by its opposite ends to opposite free ends of the primary levers; two opposed axial action thrust accumulators, defined on the central body; a loading element of the axial action thrust accumulators configured to induce a compression in the thrust accumulators following a traction of the nocking string.

BACKGROUND OF THE INVENTION 1. The Field of the Invention

The invention relates to a bow-type throwing tool.

2. The Relevant Technology

Generally a bow comprises:

-   -   two limbs, which represent the elastically deformable parts;    -   two tips, to which one end of a loading string is constrained;

a loading string, through which the arrow is loaded and the bow isflexed;

-   -   a central riser, typically rigid, which joins the limbs.

Typically, there is a handle and an arrow rest on the central riser.

Today a type of bow that is known in jargon as the ‘compound bow’, isknown and widespread, which has an eccentric pulley system that allowsstoring a greater amount of muscle energy in the limb system andreducing by a percentage, which normally ranges from 40% to 90%, theeffort when the bow is stretched.

In jargon, the term let-off refers to that effect, generated by themechanism, which allows pulling the thread or string of a compound bowor similar, reaching the full draw of the bow with a visibly reducedmuscular effort compared to the traditional bow, in addition to allowingthe shooter to remain with reduced effort in an aiming position withfull drawn bow.

The let-off is measured with a percentage which represents the value ofreduction in the effort necessary to maintain the bow completely drawn;for example, to maintain a bow loaded at 60 pounds drawn with a 70%let-off, we must exert an effort equal to only the remaining 30% of 70pounds, i.e., 18 pounds.

The let-off, obtainable with the first compound bows with percentagesfrom 35% to 50%, has significantly increased over the years and it iscurrently normal to find bows with let-off percentages of 80%.

In general, a bow is a mechanical system, as established by thestandard, which transfers the energy stored during the loading step,known as the “draw”, to the arrow which transforms said energy intokinetic energy. The amount of energy that the arrow receives depends onthe configuration of the bow, as can be clearly seen from the graphs inFIG. 42 and FIG. 43.

The energy available in a bow is equal to the work done in the drawstep, that is, it is equal to the product of the traction force, whichvaries as a function of the draw, multiplied by the variation of thedraw itself. By integrating said product over the full draw, the workdone and therefore the stored energy are obtained.

In the graphs of FIGS. 42 and 43 the draw is indicated on the abscissaand the force for achieving said draw on the ordinate.

More simply, the work, and therefore the stored energy, is equal to thearea subtended by the graph of the traction force as a function of thedraw, as can be seen in the graphs of FIGS. 42 and 43.

In the archery sector, maximum traction forces defining size, orcapacity, of the bow itself have been defined. In fact, bows of 40 lbs(the measurement unit of reference in this sector are the force-pounds),50 lbs, 60 lbs etc. are defined; this means that the traction force mustnever exceed 40 lbs, 50 lbs, 60 lbs, etc.

As a consequence of this, the maximum energy stored by a bow is given bythe product of the traction force of reference (40 lbs, 50 lbs, etc.)multiplied by the draw and is represented by a rectangle, for examplethe rectangle a-b-c-d of FIG. 42.

The graph of FIG. 42 shows, by way of example, the stored energy of atraditional bow. Said energy is represented by the triangle “a-c-d”.

The graph of FIG. 43 shows, by way of example, the energy of a compoundbow with cams. With said type of bow, the area of the polygon a-c-d-f″-ftends to be reduced to a scalene trapezoid a-c-d-f as the let-offincreases.

As can be seen from what is written above, the usable energy is always afraction, more or less large, of the maximum obtainable, represented bythe area of the rectangle with a base equal to the draw and height equalto the maximum traction force that is typical for the size of the bow.

The compound bow therefore allows to transmit to the arrow a greateramount of energy, therefore greater speed, compared to a traditionalbow, with the same load, i.e., a longbow, and to be more accurate in theaiming step.

Said compound bows, although widespread and appreciated, have somelimitations.

A first limitation of such known bows consists in the fact that in orderto vary the load capacity of a bow beyond a certain range, it isnecessary to replace the limbs, where possible, and to adjust thepre-load of the limbs themselves.

Said operations are often cumbersome and therefore difficult to carryout in a short time and without special equipment; above all, thereplacement of the limbs requires the availability of other differentand adequate limbs and specific equipment for the set-up of the bow withthe new limbs.

A second limitation of the known bows consists in the let-off, whichdespite of having reached good levels nowadays it however involves animportant physical effort for the shooter who needs time and stabilityto aim in the best possible way.

A third limitation of the bows of the known type consists in thestructural complexity of the known compound bows, comprising, inaddition to the central riser and the limbs, also pulleys, cams or othereccentric elements, double threads placed side by side with the need toadopt a special thread separator, as well as assembly and adjustmentcomponents of said components.

SUMMARY OF THE INVENTION

The aim of the present invention is to provide a bow-type throwing toolcapable of overcoming the aforementioned drawbacks and limitations ofthe prior art.

In particular, an object of the invention is to provide a bow-typethrowing tool that is simpler and faster to calibrate and adjust.

Another object of the invention is to provide a throwing tool with whicha better let-off can be achieved with respect to the bows of the knowntype.

Another object of the invention is to provide a structurally simpler andeasier to use bow-type throwing tool.

Another object of the invention is to develop a bow-type throwing toolwhich has the capability of transmitting a much higher amount of energyto an arrow than known devices already on the market.

The aforementioned task and objects are achieved by a bow-type throwingtool according to claim 1.

Additional features of the bow-type throwing tool according to claim 1are described in the dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The task and the aforementioned objects, together with the advantagesthat will be mentioned below, are highlighted by the description of anembodiment of the invention, which is given, by way of non-limitingexample, with reference to the accompanying drawings, wherein:

FIG. 1 represents a side view of a throwing tool according to theinvention;

FIG. 2 represents a rear view of the throwing tool of FIG. 1 accordingto the invention;

FIG. 3 represents a sectional side view of a detail of the throwing toolof FIG. 1;

FIG. 4 represents a side view of the throwing tool according to theinvention in an intermediate extension arrangement;

FIG. 5 represents a side view of a detail of FIG. 4;

FIG. 6 represents a detail of FIG. 5;

FIG. 7 represents a side view of the throwing tool according to theinvention in a maximum extension arrangement;

FIG. 8 represents a side view of a detail of FIG. 7;

FIG. 9 represents a detail of FIG. 8;

FIGS. 9A and 9B each represent a detail of FIG. 8 in two differentoperating arrangements of the invention;

FIG. 10 represents a first variant embodiment of the tool according tothe invention;

FIG. 11 represents a sectional side view of the first variant embodimentof FIG. 10;

FIG. 12 represents a step of use of the first variant embodiment of thethrowing tool according to the invention;

FIG. 13 represents a side view of a second variant embodiment of athrowing tool according to the invention;

FIG. 14 represents a step of use of the tool of FIG. 13;

FIG. 15 represents a variant of a detail of a throwing tool according tothe invention;

FIG. 16 represents a section view of the detail of FIG. 15;

FIG. 17 represents a side view of a throwing tool according to theinvention in one of its variant embodiments in a rest arrangement;

FIG. 18 represents the same section view as FIG. 17;

FIG. 19 represents a side view of the throwing tool according to theinvention in the variant embodiment of FIG. 17, in a maximum extensionarrangement;

FIG. 20 represents a side view of a portion of a throwing tool accordingto the invention in one of its further variant embodiments in a restarrangement;

FIG. 21 represents a section view of the same side view as FIG. 20;

FIG. 22 represents a front view of the throwing tool in the variant ofFIG. 20;

FIG. 23 represents a detail of FIG. 21;

FIG. 24 represents the same section view as FIG. 21 in a final extensionarrangement;

FIG. 25 represents a detail of FIG. 24;

FIG. 26 represents a side view of a portion of another variantembodiment of a throwing tool according to the invention;

FIG. 27 represents a sectional side view of the tool of FIG. 26;

FIG. 28 represents a front view of the tool of FIG. 26;

FIG. 29 represents a sectional front view of the tool of FIG. 26;

FIG. 30 represents a sectional side view of a detail of the tool of FIG.26, in an intermediate operating arrangement;

FIG. 31 represents the same sectional side view as FIG. 30 in asubsequent intermediate operating arrangement;

FIG. 31A represents a detail of FIG. 31;

FIG. 32 represents a detail of FIG. 31;

FIG. 32A represents a detail of FIG. 32;

FIG. 33 represents the same sectional side view as FIG. 30 in anarrangement at the beginning of the unloading step;

FIG. 34 represents a sectional side view of a variant embodiment of theinvention;

FIG. 35 represents a front view of a detail of the invention in one ofits variant embodiments;

FIG. 36 represents a section view of a portion of the detail of FIG. 35in a first possible arrangement of use;

FIG. 37 represents a section view of a portion of the detail of FIG. 35in a second possible arrangement of use;

FIG. 38 represents a section view of a portion of another variantembodiment of the detail of FIG. 35, in a first configuration of use;

FIG. 39 represents a section view of a portion of the variant of FIG.38, in a second configuration of use;

FIGS. 40 and 41 represent a throwing tool according to the invention ina different structural form;

FIGS. 41A and 41B each represent a section view, respectively in planand lateral view, of the throwing tool of FIGS. 40 and 41;

FIGS. 42 and 43 represent energy storage graphs referring to archerytools of the known type;

FIGS. 44 to 47 each represent an energy storage graph referring tobow-type throwing tools according to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to the cited Figures, a bow-type throwing tool accordingto the invention is indicated as a whole with number 10.

This bow-type throwing tool 10 comprises a central body 11, a nockingstring 12 for an arrow, and elastic energy storage means 13 operated bythe traction of the string 12.

The peculiarity of the archery tool 10 according to the inventionresides in the fact that the means for storing elastic energy 13comprise:

-   -   two opposed primary levers 14 and 15 connected with hinging        means 16 to the central body 11; the nocking string 12 is        constrained by its opposite ends 12 a and 12 b to opposite free        ends 17 and 18 of the primary levers 14 and 15;    -   two opposed axial action thrust accumulators 19 and 20        respectively, defined on the central body 11;    -   loading means 21 of said axial action thrust accumulators 19 and        20, which loading means 21 are configured to induce a        compression in the thrust accumulators 19 and 20 following a        traction of the nocking string 12.

The central body 11 comprises a part with a predominantly longitudinaldevelopment 22.

The part with a predominantly longitudinal development 22 is configuredso as to define a handle 23 and an arrow rest area 24.

The central body 11 also comprises two opposite frames 25 and 26 eachdefining a window, inside each of which windows there is a correspondingthrust accumulator 19 and 20.

The ‘front side’ is defined as the side of the throwing tool 10 turnedto the direction of exit of a thrown arrow, and the ‘rear side’ isdefined as the opposite side of the same throwing tool 10.

The central body 11 comprises hinging appendages 27 and 28 respectively.

Said hinging appendages 27 and 28 develop from the part of the rear sideof the central body 11.

Said hinging appendages 27 and 28 develop from the central body 11 atthe frames 25 and 26.

In the present, obviously non-limiting embodiment example of theinvention, said hinging appendages 27 and 28 have a trilateral shape.

The nocking string 12 for an arrow can consist of a single thread oralternatively of a braid of threads, and in any case it is to beunderstood a string of a type known per se.

In the form described herein of the invention, to be understood as anexample and not limiting of the invention itself, each of the twoopposed primary levers 14 and 15 comprises an ‘L’-shaped body.

Each primary lever 14 and 15 comprises a free end 17 and 18 respectivelyand an opposite pivoting portion 29 and 30.

Each pivoting portion 29 and 30 is designed for the connection, by meansof the hinging means 16, to a corresponding hinging appendage 27 and 28of the central body 11.

Each primary lever 14 and 15 has a return appendage 17 a and 18 arespectively, equipped with a rest element 17 b and 18 b for the nockingstring 12 when the throwing tool 10 is in the rest arrangement, as shownin FIGS. 1, 2 and 3.

Said rest element 17 b and 18 b can consist, for example, of a bearing,or of a simple pin, or other cylindrical or disc-shaped element, fixedor rotatable around its main axis.

The hinging means 16 comprise a pin 31, clearly visible in particular inFIG. 6; said pin 31 is connected to the central body 11, and inparticular to the respective hinging appendage 27 or 28, by means offriction reduction means of a type to be understood as known, such asfor example two rolling bearings.

In the variant embodiment of the invention described herein by way ofnon-limiting example of the invention itself, each of the axial actionthrust accumulators 19 and 20, respectively, comprises at least onecompression load spring.

In particular, in the present embodiment example, an axial action thrustaccumulator 19 and 20 comprises a plurality of Belleville springs 40,arranged in series with each other, as clearly visible in FIG. 3.

Still in particular, in the present embodiment example, the thrustaccumulator 19 and 20 comprises at least two groups of load springs 40and 41, for example three groups of load springs 40, 41 and 42.

Advantageously, said groups of load springs 40, 41, 42 havedifferentiated stiffnesses.

An axial action thrust accumulator 19 and 20 comprises at one end afixed head 43 and at the opposite end a movable head 44.

The axial action thrust accumulator 19 and 20 comprises a stem 45,translatable in the direction of its own axis X, to which the movablehead 44 is constrained.

X is therefore the axis of the stem 45.

The above indicated at least one compression load spring is centrallycrossed by a stem; for example, the groups of load springs 40, 41 and 42are crossed centrally by the stem 45.

The stem 45 has a manoeuvring end 45 a, available for the connection tothe loading means 21.

The loading means 21, configured to induce a compression in the thrustaccumulators 19 and 20 following a traction of the nocking string 12,are hereinafter described as in no way limiting embodiment example ofthe invention.

Said loading means 21 comprise:

-   -   a loading thread 47, which is fixed at a first end to the        central body 11 and at the opposite second end to a        corresponding primary lever 14 or 15;    -   a pulley system configured to cause a translation of the stem        45, for it to exit the frame 25 or 26, i.e., along the line of        said axis X and in the compression direction of a corresponding        thrust accumulator 19 and 20, following a traction of the        loading thread 47.

Said pulley system comprises, for example, two pulleys, a first pulley48 hinged to the manoeuvring end 45 a of the stem 45, and a secondpulley 49 hinged to the central body 11.

In particular, the loading thread 47 is fixed at a first end to a fixedpin 50, integral with the central body 11, and at the second end to amovable pin 51, which is instead rotatably constrained to acorresponding primary lever 14 or 15.

The traction of the nocking string 12 by a user causes the simultaneousrotation in a load direction of the primary levers 14 and 15.

The rotation of the primary levers 14 and 15 in the respective loaddirection causes the rotation of the movable pins 51, each integral witha primary lever 14 and 15, according to a trajectory moving away fromthe corresponding fixed pin 50.

Said movement of the movable pins 51 causes the traction of the loadingthreads 47 and, through the pulleys 48 and 49, the translation of thestems 45 for them to exit the respective frames 25 and 26.

The translation of the stems 45 causes the movable heads 44 to movecloser to the respective fixed heads 43 of the thrust accumulators 19and 20 and therefore the loading of the same thrust accumulators 19 and20.

The thrust accumulators 19 and 20 are said to have an axial action sinceonce they are brought into compression they exert a thrust in thedirection of their own main axis X.

In particular, in the present embodiment example, the axial actionthrust accumulators 19 and 20 are advantageously coaxial with eachother.

The thrust accumulators 19 and 20 each have a single degree of freedomin a direction, which is a vertical direction in the exemplary Figures,indicated by the axis X, of the crushing of the pack of Bellevillesprings placed in series with each other.

Also each of the primary levers 14 and 15, with respect to the centralbody 11, has only one degree of freedom, that is it can only rotatearound the axis identified by the cylindrical seat where the rollingbearings are housed.

The thrust force exerted by each of the thrust accumulators 19 and 20,i.e., by the compressed Belleville springs described in the presentembodiment example, is transmitted from the central body 11 to theprimary levers 14 and 15 through the loading thread 47.

Said force tends to rotate the primary levers 14 and 15 towards thefront side of the throwing tool 10, opposing a possible rotation of thesame primary levers 14 and 15 in the opposite direction.

The rotation of the primary levers 14 and 15 in the direction which isindicated below as the ‘unloading direction’, i.e., towards the frontside of the throwing tool 10, ends when the string 12, by resting on therest elements 17 b and 18 b, reaches the rest arrangement, as visible inFIGS. 1 to 3.

The nocking string 12 is fixed at its ends to corresponding locking pins60, which are free to rotate around their axis with respect to theprimary lever 14 or 15 which carries them.

The primary levers 14 and 15 rotate until the nocking string 12 iscompletely drawn as exemplified in FIG. 7.

The load of the springs, partially or completely compressed, creates atension both on the loading thread 47 and on the nocking string 12.

FIG. 3 shows a first variable lever arm A of the loading string 47 and asecond variable lever arm B of the nocking string 12.

By observing the system from this point of view, the primary levers 14and 15 rotate in the unloading or loading direction according to whetherthe torque exerted by the thrust accumulators 19 and 20 exceeds or isless than the torque exerted by the nocking string 12.

FIGS. 4 to 6 show an intermediate arrangement of use of the throwingtool 10 according to the invention.

In said intermediate arrangement, the nocking string 12 is pulled with aforce applied at the nocking point P, to be understood as positionedhalfway of the nocking string

The torque exerted by the nocking string 12, pulled at point P by thehand of a user, possibly by means of suitable tools of the known typecalled in the sector with the term ‘releases’, on each of the primarylevers 14 and 15, is higher than the torque achieved by the thrustaccumulators 19 and 20, whereby the primary levers 14 and 15 rotate inthe loading direction, whereby the moving away of the nocking point Pfrom the central body 11 is favoured.

The stems 45 of the thrust accumulators 19 and 20 tend to be extractedfrom the respective frames 25 and 26, moving towards the respectivemaximum extraction position. Consequently, the Belleville springs,stacked in series on said stems 45, tend to become more and morecrushed, increasing more and more the amount of elastic energy stored.

The variable lever arms A and B vary as a function of the rotation ofthe corresponding primary lever 14 or 15; in particular, the first leverarm A, of the loading thread 47, tends to decrease while the secondvariable lever arm B, of the nocking string 12, tends to increase, asclearly visible by comparing FIGS. 3, 4 and 6, with a multiplier effectthat allows storing a high level of elastic energy when compared to theshooting force at point P of the nocking string 12.

FIGS. 7 to 9 show the throwing tool 10 according to the invention in itsmaximum extension arrangement.

In said arrangement, the primary levers 14 and 15 have reached theirrespective final position of maximum load; in fact, each lever 14 and 15rests against a striker portion 11 a of the central body 11, thereforeit cannot rotate further in the loading direction, regardless of theforce achieved on the nocking string 12.

The stem 45 of each accumulator 19 and 20 has reached the maximum designextraction position and the relative springs 40, 41 and 42 reach theirmaximum rated design compression and, consequently, exert their maximumdesign force.

The variable lever arms, first arm A of the loading string 47, clearlyvisible in FIG. 9, and second arm B of the nocking string 12, indicatedin FIG. 7, reach their final size at completion of the design draw.

A notch 31 a is made on said pin 31 for the passage of the loadingthread 47, said notch 31 a being configured to allow the progressivereduction of the distance between the axis X47 of the loading thread 47and the rotation axis X31 of said pin 31 during the traction step of thenocking string 12.

The pin 31, at the notch 31 a, has a solid part 31 b configured todefine a curved surface 31 c for the rest of the loading thread 47.

Hence, the notch 31 a is concave and the solid part 31 b of the pin 31is correspondingly convex.

The curved surface 31 c has a cusp 31 d.

The axis X31 of the pin 31 crosses the pin 31 at the notch 31 a, and notat the solid part 31 b.

The distance between the axis X47 of the loading thread 47 and therotation axis X31 of the pin 31 is indicated in FIG. 9B with the symbolD and corresponds, that is coincides, to the variable lever arm Adescribed above.

The distance between the cusp 31 d and the rotation axis X31 of the pin31 is indicated with the symbol Z, as shown in FIG. 9A.

Said distance Z is less than the radius of the loading thread 47.

In particular, and by way of example, said notch 31 a is shaped in sucha way that the axis X47 of the loading thread 47 stops at a distance Dfrom the axis X31 of the pin 31 which can be comprised between 1 and 5hundredths of a millimetre.

The distance D between the axis X31 of the pin 31 and the axis X47 ofthe loading thread 47 corresponds to the difference between the radiusof the loading thread 47 and the distance Z between the cusp 31 d andthe axis X31 of the pin 31.

Said notch 31 a develops like an arc of a circle over an angle comprisedbetween 180° and 200°, and in general greater than 180°.

In particular, therefore, the distance D of the axis X47 of the loadingthread 47 from the rotation axis of the pin 31 is near zero, remaininggreater than zero, to allow the rotation in the unloading direction oncethe force generating the draw has been zeroed, that is when the userreleases the string 12.

Said situation occurs thanks to the notch 31 a made on the rotation pin31 of each primary lever 14 and 15, and clearly visible in FIGS. 6, 9,9A and 9B, so that, when a primary lever 14 and 15 is in the arrangementof maximum extension of the throwing tool 10, the axis X47 of theloading thread 47 almost intersects the rotation axis X31 of the pin 31.Furthermore, the notch 31 a is made in such a way that the distance ofthe axis X47 of the loading thread 47 from the rotation axis X31 of thepin 31 is always greater than zero. In fact, the loading thread 47 restson the cusp 31 d of the notch 31 a which is at a distance, from therotation centre, less than the radius of the loading thread 47 itself,thus ensuring that the distances between the axes are always greaterthan zero.

In this way the torque exerted by the loading thread 47 on the primarylever 14 does not change its sign.

Once the draw force has been zeroed, when the arrow nocked on the string12 is released, the torque achieved by the nocking string 12 is equal tozero while the force of the axial action thrust accumulators 19 and 20is greater than zero, and therefore the levers 14 and 15 move in theunloading direction, shifting to the rest arrangement of FIGS. 1, 2 and3.

The combination of the variable lever arms A, i.e., the distance D, andB during the loading step is such that, depending on the draw, the forcenecessary to achieve said draw has a trend represented by the graphshown in FIG. 44, where the abscissa shows the draw in millimetres andthe ordinate the force for achieving said draw expressed in Newton.

Said trend is an example, since numerous variants of the trend of thegraph shown in FIG. 44 are possible, as for example in the graphs ofFIGS. 45 and 46. Each of said graphs is to be intended as referring to asingle thrust accumulator 19 and 20, and not to the total energy storageachieved by both thrust accumulators operated simultaneously during adraw.

Said trend shows that the let-off at the maximum draw is very low andthe reduction in the loading effort is reduced by more than 90%.

The thrust accumulators 19 and 20 of the invention lead to the followingadvantages:

-   -   thanks to the coaxial and opposed position, at the end of the        return stroke the blocking forces of the two accumulators 19 and        20 are opposed and cancel out each other; in this way, the        perturbation on the system, when the end of stroke is reached,        is much reduced;    -   in the bows with known limbs, the load on the bow can be varied        either by replacing the limbs, thus switching from a predefined        level to another one, or by adjusting their pre-load; thanks to        the throwing tool 10 according to the invention, by varying the        type and size of the load springs that make up the accumulators        19 and 20, it is possible to vary the load gradually, and by        varying the amount of the springs it is possible to obtain a        graph of more personalized load;    -   the possible breakage of a spring allows in any case the        operation of the throwing tool 10, contrary to the bows with        limbs of the known type;    -   the pre-load, or the load on the loading thread 47 in the rest        configuration, can be easily varied by acting on a nut 80 which        closes the springs on the stem 45.

As mentioned above, the first variable lever arm A of the loading thread47 is determined by the distance between the axis of the loading thread47 itself and the axis of the unloaded pin 31 of the correspondingprimary lever 14 or 15.

In the example described and illustrated herein, the unloaded pin 31rotates integrally with the primary lever 14 or 15, but alternativelythe pin 31 can be integral with the central body 11. In this case, thelever 14 and 15, equipped with suitable bearings, would rotate aroundits own pin 31.

The variable lever arm A of the loading thread 47 is reduced to almostzero when the lever 14 and 15, by rotating, reaches the position ofmaximum draw. This occurs because the loading thread 47 is fixed to amovable pin 51 which is integral with the lever 14 and 15 itself.

As the lever 14 and 15 rotates, the movable pin 51 rotates around therotation centre of the pin 31 of the lever 14 and 15, shifting to aposition such that the axis of the loading thread 47 almost coincideswith the rotation axis.

The notch 31 a of the pin 31, in addition to allowing the lever arm tobe almost zeroed, ensures that this is always greater than zero. Infact, the mechanical machining of the unloaded surface of the notch 31 ais done in such a way that the distance between the cusp and therotation axis is less than the radius of the loading thread 47 itself.

Said configuration makes it possible to reach final load reductions,i.e., ‘Let-Off ratio’ values that are higher than those of the systemson the market.

As mentioned above, each of the primary levers 14 and 15 is connected tothe central body 11 by means of the unloaded pin 31, which rotatesrigidly with the respective lever 14 and 15, and by means of two rollingbearings which allow the rotation of the lever with a friction close tozero.

The rolling bearings are connected on one side to the lever 14 or 15while on the other side they are connected to a seat defined on thecentral body 11, for simplicity not illustrated. Between the seat on thecentral body 11 and the bearing there is a rubber body, for example oneor more O-rings, for example made of NBR plastic; the presence of suchrubber bodies has the following advantages:

-   -   it reduces the vibrations generated by the nocking string 12        when it is released and it returns to the rest configuration        after the loading step;    -   it reduces the machining cost of the seat of the bearing because        the tight coupling tolerances that are typical of the bearing        seats are not required.

‘Draw Length’ means the distance between the handle and the nock pointof an arrow.

The final position of the primary levers 14 and 15 is defined by thedesign, since the central body 11 has, as mentioned, a striker portion11 a which blocks the rotation of the levers 14 and 15 themselves.

From this point, the desired draw is obtained by selecting the length ofthe nocking string 12.

In current systems, the definition of the draw is achieved by means of acam device with discrete adjustments which allows, with the samecomponents, to obtain a limited adjustment interval of the draw.

Sometimes such adjustment requires using a dedicated tool, known as a‘bow press’, to modify the attachment position of the nocking string.

With the present invention, by simply modifying the length of thenocking string 12 it is possible to obtain an almost continuousvariation of the draw from a maximum to a minimum value (said values arerelated to the size of the primary levers 14 and 15).

Furthermore, discretised variations in draw can be obtained by using thesame nocking string 12.

This is achieved, as exemplified in the variant embodiment of FIGS. 10,11 e 12, by means of a draw discretisation insert 90.

Said draw discretisation insert 90 is fixed in a hole 91 x chosen from aplurality of aligned holes 91 defined on each of the primary levers 14and 15.

By keeping the same nocking string 12 with predetermined length, andsimply choosing a hole 91 x and fixing the string 12 to the drawdiscretisation insert 90 and then the insert to the hole 91 x, it ispossible to modify the performance of the throwing tool 10 in numerousways according to the user's needs and technical requirements.

In a variant embodiment of the throwing tool according to the invention,not illustrated for simplicity, the loading thread and the nockingstring are both made of a single thread or of a single string.

The throwing tool 10 according to the invention allows making a verywide and refined variation of the load curve.

In particular, while the current technology allows a percentage oflightening of the shot in the final position (Let-Off) in the range70÷90%, the throwing tool 10 according to the invention allows to easilyreach a let-off higher than 90%, thus guaranteeing to the archer agreater relaxation during the aiming step before shooting the arrow.

A further advantage achieved by the throwing tool 10 according to theinvention is given by the fact that the configuration of the samethrowing tool 10 allows to eliminate the cables connecting the pulleysthus allowing greater visibility and better manoeuvrability for thearcher.

Furthermore, the throwing tool 10 according to the invention does notrequire the use of dedicated systems, such as adjustment benches—bowpress, for adjusting the bow shot and the draw thereof.

Furthermore, with the throwing tool 10 according to the invention, theconfiguration of the load graph can be easily adapted to the needs ofthe archer by acting, as already said, on the configuration of theaccumulators 19 and 20, i.e., of the packs of Belleville springs.

Furthermore, by acting on the pulleys 48 and 49 and on the othermechanical members of the mechanism of the loading thread 47 the desiredlet-off can be obtained.

The same variation in let-off can be obtained by varying the final,end-of-stroke, position, of the levers 14 and 15.

As mentioned above, the variation of the draw of the throwing tool 10can be made in two ways:

-   -   by varying the length of the nocking string 12, choosing a        string 12 having the preferred length;    -   by using the draw discretisation insert 90; by varying the        position of said draw discretisation insert 90 in the holes 91,        with the same length of the thread, the draw varies in a        discrete manner.

In a variant embodiment of the invention, the axial action thrustaccumulators 119, so indicated in FIGS. 15 and 16, are of the magnettype.

Such magnet thrust accumulators 119 have two magnets or electromagnets140 and 141, one of which fixed to a fixed head 143 and the other onemovable and resting on a movable head 144; the movable head 144 is fixedto the stem 145 which is in turn translated by the loading means 21, asdescribed above.

By placing the magnetic poles in opposition and moving them closeragainst each other it is possible to achieve the same dynamic actiondone by the springs.

In a further variant embodiment of the invention, exemplified in FIGS.13 and 14, each of the ends of the nocking string 12 is fixed to anintermediate rod 99, which in turn is pivoted to a corresponding lockingpin 60, as above described.

Said intermediate rod 99 has such a length so as to rest on the restelement 17 b and 18 b of the respective primary lever 14 and 15 in therest arrangement.

Said intermediate rod 99 is rigid.

The application of said intermediate rod 99 allows the adoption of ashorter, therefore less expensive, nocking string 12 and also reducesthe vibrations of the nocking string 12 itself.

In a further variant embodiment of the invention, illustrated below, thebow-type throwing tool comprises a crossbow-like structure, that is alsocomprising a gripping shaft, known in the jargon of the sector as a‘tiller’, and loading and release mechanisms for a body to be thrown.

FIGS. 17 to 19 show a different variant embodiment of the throwing toolaccording to the invention, indicated therein as a whole with number110.

In said variant embodiment, it being also obviously exemplary andnon-limiting of the invention itself, each of the two opposed primarylevers 114 comprises a circular sector shaped body.

Each primary lever 114 comprises a pivoting portion 129 defined at theaxis of the profile of the circular sector shaped body.

Each pivoting portion 129 is designed for the connection, by means ofthe hinging means 16 as described above, to a corresponding hingingappendage 27 of the central body 11, similarly to what has already beendescribed for the previous variant embodiment of FIGS. 1 to 16.

Each primary lever 114 has a curved perimeter edge 117 a, provided witha rest groove 117 b for the nocking string 12 when the throwing tool 110is in the rest arrangement, as shown in FIGS. 17 and 18.

Similarly to what has been described above, the loading thread 47 isfixed at a first end to a fixed pin 50, integral with the central body11, and at the second end to a movable pin 151, which is insteadrotatably constrained to a corresponding primary lever 114.

Also in said variant embodiment the throwing tool 110 comprises a drawdiscretisation insert 190.

Said draw discretisation insert 190 is fixed in a hole 191 x chosen froma plurality of aligned holes 191 defined on the curved perimeter edge117 a of each of the primary levers 114.

The operation of said variant embodiment is analogous to the operationof the variants described above.

As can be seen from what is written above, the usable energy is always afraction, more or less large, of the maximum obtainable energy,represented by the area of a rectangle having a base equal to the drawand height equal to the maximum traction force that is typical for thesize of the throwing tool.

To obtain more energy, it is necessary to approximate the area of therectangle described above as much as possible and, finally, to obtain anenergy greater than the area itself, it is necessary to store mechanicalenergy in advance to be released then when the arrow is released.

Two systems have been developed to meet said needs. A first system,exemplified in FIG. 20, optimises the approximation of the area of therectangle. A second system, exemplified in FIG. 26, stores in advancemechanical energy.

Both systems are configured in such a way that the stored energy isreleased to the arrow, together with that of the thrust accumulator 19and 20, when it is released upon completing the draw.

Therefore, in a variant of its embodiment shown in Figures from 20 to25, the bow-type throwing tool 210 according to the invention alsocomprises a pair of load increase devices 261, configured to operate inseries with a corresponding thrust accumulator 19 and 20.

The Figures show, by way of example, only one of said load increasedevices 261, whereby the other opposite load increase device not shownis intended as being equal.

Said load increase device 261 comprises:

-   -   a stem 245 of the thrust accumulator 19, which is equipped with        a striker head 262,    -   a containment box 263, fixed externally to the end of the frame        25,    -   a slider body 264 placed so as to translate, along the thrust        axis X of the corresponding thrust accumulator 19, into a        through hole 265 defined at the end of the frame 25 and into a        coaxial guide hole 266 defined in the containment box 263,    -   a plurality of thrust increase springs 267 and 268, placed so as        to act between a cover 269 of the containment box 263 and a        shoulder 270 of the slider body 264.

The slider body 264 also comprises an abutment element 271, configuredto abut against the striker head 262 of the stem 245.

Said abutment element 271 is configured to be able to adjust the axialposition with respect to the slider body 264 itself, with the aim ofdefining the distance with the striker head 262.

The abutment element 271 consists for example of a screw screwed axiallyto the slider body 264.

Alternatively, the abutment element 271 can be fixed permanently to theslider body 264 or it can also be made in a single piece with the sliderbody 264.

The containment box 263 comprises the cover 269 and a spacing side wall272.

The cover 269 is fixed to the end of the frame 25 by means of threadedconnections 269 a of a type known per se.

Said load increase device 261 works as follows.

When the user pulls the nocking string 12, the stem 245 translates,pulled by the loading thread 47, until it abuts against the abutmentelement 271; afterwards, the traction by the user causes the thrust ofthe stem 245 on the slider body 264 and the consequent compression ofthe increase springs 267 and 268, with a further storage of throwingenergy in the same increase springs 267 and 268, as exemplified in theFIGS. 24 and 25.

When the user releases the nocking string 12, a thrust force istransmitted to the primary lever 214 which force comprises both theaction of the springs of the thrust accumulator 19 and the action of theincrease springs 267 and 268 of the load increase device 261.

The load increase device 261 can also comprise a stroke limiter 273 forlimiting the stroke of some of the increase springs 267 and 268.

For example, said stroke limiter 273 consists of a cup comprising a discbase 273 a and a cylindrical wall 273 b in which some increase springs268 are housed, the stroke of which is to be limited, thus adjusting theaction of the same.

In fact, during the crushing step of the increase springs 268 thecylindrical wall of the stroke limiter 273 will rest against the cover269, preventing the increase springs 268 contained in the stroke limiter273 itself from being further crushed.

FIG. 45 shows a graph in which the draw in millimetres is indicated onthe abscissa and the force for achieving said draw expressed in Newtonson the ordinate; in this graph a dashed line indicates a pull curve inthe absence of the load increase device 261, while a solid lineindicates a pull curve in the presence of the load increase device 261

In a further variant embodiment shown in Figures from 26 to 34, thebow-type throwing tool 310 according to the invention also comprises apair of pre-loadable external auxiliary accumulators 361 configured tooperate in series with a corresponding thrust accumulator 19 and 20.

In this way an energy higher than that represented by the Pull-Drawrectangle is obtained.

The Figures show, by way of example, only one of said pre-loadableexternal auxiliary accumulators 361, whereby the other oppositepre-loadable external auxiliary accumulator not shown is intended asbeing equal.

Said pre-loadable external auxiliary accumulator 361 comprises:

-   -   a stem 345 of the thrust accumulator 19, which is equipped with        a striker head 362;    -   a containment box 363, fixed externally to the end of the frame        25;    -   a first slider body 364A placed so as to translate, along the        thrust axis X of the corresponding thrust accumulator 19, into a        through hole 365 defined at the end of the frame 25;    -   a second slider body 364B placed so as to translate, along the        thrust axis X, into a guide hole 366 a defined on the first        slider body 364A and into a coaxial guide hole 366 b defined in        the containment box 363;    -   a plurality of thrust increase springs 367, placed so as to act        between a cover 369 of the containment box 363 and a first        shoulder 370 of the second slider body 364B; said thrust        increase springs 367 are, for example, Belleville springs;    -   a pre-load lever 381, pivoted to a bracket 382, developing from        the cover 369, through a pin 383;    -   a pre-load tie rod 384 constrained at a first end 384 a to a        first traction pin 385 fixed to the second slider 364B, and at        the opposite second end 384 b to a second traction pin 386 fixed        to the pre-load lever 381; the pre-load tie rod 384 for example        consists of a flexible element, for example a cord, with two        opposite end slots; the end slots allow the swivel constraint        with the pins 385 and 386; alternatively, said pre-load tie rod        consists of a rigid element;    -   an elastic return element 387 constrained on one side to the        cover 369 and on the opposite side to the pre-load lever 381;        said elastic return element 387 is, for example, a helical        spring operating in traction.

The pre-loadable external auxiliary accumulator 361 can comprise, likein the embodiment example from FIG. 26 to FIG. 33:

-   -   one or more accompanying springs 368, placed so as to act        between the first shoulder 370 of the second slider body 364B        and a facing second shoulder 370 a of the first slider body        364A; said accompanying springs 368 are, for example, Belleville        springs; the

Figures show a single accompanying spring 368, but it is to beunderstood that there may also be two or more;

-   -   a stroke adjustment system for said accompanying springs 368,        defined below by way of example by the striker perimeter wall        370 b, clearly visible in FIGS. 31 and 33, of the first slider        body 364A.

The pre-load lever 381 can be manoeuvred by means of a manoeuvring rod388, reversibly inserted in a corresponding fixing hole 381 a defined onthe same pre-load lever 381

The first slider body 364A also comprises an abutment element 371,configured to abut against the striker head 362 of the stem 345.

Said abutment element 371 is configured to be able to adjust its ownaxial position with respect to the first slider body 364A itself andwith the aim of defining the distance with the head 362.

The abutment element 371 consists for example of a screw screwed axiallyto the first slider body 364A.

Alternatively, the abutment element 371 can be fixed permanently to theslider body 364, or it can also be made in a single piece with theslider body 364.

The containment box 363 comprises the cover 369 and a spacing side wall372.

The cover 369 is fixed to the end of the frame by means of threadedconnections 369 a of a type known per se.

The configuration of a pre-loadable external auxiliary accumulator 361in a non-loaded arrangement is shown in FIGS. 26, 27 and 29.

In said arrangement, the draw is equal to zero and the group comprisingthe pre-load lever 381, the elastic return element 387, the pre-load tierod 384 and the thrust increase springs 367, is in the rest position.

In said arrangement, in particular, the pre-load lever 381 is rotated tothe right, with respect to the representation of FIGS. 26 and 27, theelastic return element 387 exerts a very small or null force and thethrust increase springs 367, as well as the accompanying springs 368,are completely unloaded and therefore open, in the sense of “notcompressed”.

In said non-loaded arrangement, the adjustment screw with the abutmentelement 371 is positioned at a distance established by the head 362 ofthe stem 345. In said configuration, the removable manoeuvring rod 388is inserted in its fixing hole 381 a on the pre-load lever 381.

The loading step is represented in FIGS. 28, 30, 31 and 33.

Loading takes place by applying a force on the manoeuvring rod 388,removable, so as to cause a torque capable of rotating the pre-loadlever 381 anticlockwise with reference to FIGS. 30 and 31 with respectto its pin 383.

Said rotation, starting from the rest position of the load-absentarrangement described above, tends to displace the second traction pin386, integral with the pre-load lever 381, moving it away from the endof the frame 25; said displacement of the second traction pin 386 causesa displacement in the axial direction X of also the first traction pin385 being moved away from the end of the frame 25, which displacement iscaused by the pre-load tie rod 384 which connects the two traction pins385 and 386.

The first traction pin 385 is, in turn, rigidly connected to the secondslider body 364B, which is translated in the same way.

The movement, along the axis X, of the second slider body 364B beingmoved away from the end of the frame 25 in turn causes the crushing ofthe thrust increase springs 367 which cannot move vertically as they areresting, possibly by means of an adjustment shim 389, on the cover 369;the cover 369 supports the pre-load lever 381 and is rigidly fixed tothe spacing walls 372 and to the frame 25 which in turn is part of thecentral body 11.

The crushing of the springs generates an elastic force transmitted tothe pre-load lever 381 through the pre-load tie rod 384.

The mutual position of the pin 383 of the pre-load lever 381, of thefirst traction pin 385 and of the second traction pin 386 is such that,in the non-load arrangement, the longitudinal axis of the pre-load tierod 384 is located, with respect to the Figures, on the right side ofthe rotation axis of the pin 383 of the pre-load lever 381, as shown inFIGS. 26 and 27.

The pin 383 is positioned with an axis parallel to the axis of the firsttraction pin 385.

The axes of said pin 383 and of said first traction pin 385 lie on thesame plane passing through the axis X; the axes of the pin 383 of thepre-load lever 381 and of the first traction pin 385 are thereforealigned in the direction of the axis X of action of the thrustaccumulators 19 and 20.

Said elastic force therefore generates a torque, which opposes therotation of the pre-load lever 381, equal to the product of the distanceof the axis of the pre-load tie rod 384 from the rotation centre of thepin 383, multiplied by the elastic force itself. Naturally, in order tocontinue the loading step, the torque exerted through the removablemanoeuvring rod 388 must be higher than the resistant one exerted by thetie rod 384.

When the tie rod 384 is with its axis aligned with the line joining therotation centres of the two pins 383 and 385, there is a configurationof maximum crushing of the springs during the loading step; in such anarrangement of maximum crushing of the springs the resistant torque isnull since the arm of the torque is null; the torque caused by theelastic return element 387 is neglected because it is very low in saidarrangement.

Continuing the anticlockwise rotation, through the force applied to theremovable manoeuvring rod 388, the axis of the pre-load tie rod 384switches from the position of null arm to a position inclined towardsthe left, always with reference to the relative Figures.

In said arrangement, the torque exerted by the force of the springstends to accelerate the anticlockwise rotation, lowering the height ofthe second upper traction pin 386 and of all the elements connectedthereto.

The anticlockwise rotation of the pre-load lever 381 is interrupted whenthe same pre-load lever 381 abuts against a stop end element 390; saidstop end element 390 consists, for example, of a flat appendage whichdevelops from the cover 369 and is integral therewith.

The pre-load lever 381 has a rest tooth 381 b configured to abut againstthe stop end element 390.

At this point, the removable manoeuvring rod 388 can be removed and theexternal auxiliary accumulator 361 assumes the configuration shown inFIG. 30.

The elastic return element 387, switching from the non-load arrangementto the load arrangement, undergoes an elongation and therefore generatesa force, clockwise, which tends to return the pre-load lever 381 to theinitial non-load arrangement.

The torque generated by the force of the elastic return element 387 ishowever much lower than the torque, operating in an anticlockwisedirection, caused by the pack of thrust increase spring 367 through thepre-load tie rod 384, whereby the pre-load lever 381 remains blocked insaid holding arrangement.

The stored pre-load energy, in said step, is equal to the work done todeform all the pre-load springs.

It should be noted that the whole action described above does not affectthe accompanying spring 368, if present, and the relative first sliderbody 364A; in fact, their position remains unchanged like all the othercomponents of the archery tool 310, i.e., the main lever 314, theloading thread 47, the nocking string 12 and the thrust accumulators 19and 20.

The step for releasing the energy stored in the thrust increase springs367, as well as the action of one or more accompanying springs 368 aredescribed below.

In said release step, a user begins to load an arrow nocked on thenocking string 12, increasing the draw and bringing it to its maximumvalue.

As a consequence thereof, the primary lever 314 starts rotating aroundthe rotation axis of the rotation pin 31.

The loading thread 47, with one end integral with the primary lever 314,is pulled and this causes the part of the thread engaged between thefixed pin 50 and the second pulley 49 to shorten; as a consequence thereis a traction, through the first pulley 48, of the stem 345 in thedirection of the axis X, the head 362 of which moves towards theabutment element 371 of the first slider body 364A.

At a certain draw and, therefore, at a certain rotation of the primarylever 314, the head 362 of the stem 345 reaches the abutment element371.

By continuing to increase the draw, the stem 345 translates further,further pushing the first slider body 364A outwards, in the direction ofthe axis X.

The stem 345 further translates, further pushing outwards, in thedirection of the axis X, the first slider body 364A together with theaccompanying spring 368, when the latter is present, until the sameaccompanying spring 368 touches the lower surface of the first shoulder370, as shown in FIG. 31.

The second slider body 364B is pushed towards the centre of the centralbody 11 by the force of the thrust increase springs 367 and is held insaid position by the pre-load tie rod 384.

The force of the thrust increase springs 367 is much higher than the oneexerted by the accompanying spring 368, and consequently, by continuingto increase the draw, the stem 345 continues to rise by crushing theaccompanying spring 368 against the lower surface of the second sliderbody 364B. Said crushing continues until the first slider body 364Arests on the lower surface of the second slider body 364B.

The stroke adjustment system for the accompanying springs 368 comprisesone or more striker perimeter walls 370 b, fixed, or alternativelyresting, to the second shoulder 370 a of the first slider body 364A, asclearly visible in FIG. 31; the stroke adjustment system can comprise asingle continuous perimeter wall or several perimeter walls spaced apartfrom each other along the same perimeter.

The one or more striker perimeter walls 370 b are configured to abutagainst the first shoulder 370 of the second slider body 364B andtherefore to limit the crushing of one or more accompanying springs 368.

At this point, the further increase in the draw and the consequentfurther translation of the rod 345 outwards in the direction of the axisX cause a further crushing of the thrust increase springs 367 inaddition to that defined by the action of the pre-load lever 381 throughthe tie rod 384.

In said arrangement, the imposed draw has not been reached yet andconsequently the primary lever 314 must still rotate to reach it, i.e.,the axis of the loading thread 47 is at a certain distance from the axisof the pin 31 of the primary lever 314.

To reach the established draw, the nocking string 12 is to be furtherpulled, with consequent rotation of the primary lever 314 which rotatesuntil it is blocked against a stop end. This obviously involves afurther translation of the stem 345 together with the second slider body364B and a consequent further crushing of the thrust increase springs367.

When the distance between the first traction pin 385, integral with thesecond slider body 364A, and the second traction pin 386, integral withthe pre-load lever 381, is smaller than the length of the pre-load tierod 384, the pre-load tie rod 384 is loose, stops operating in tractionand consequently the whole force, exerted by the thrust increase springs367, is supported by the rod 345.

Said increase in thrust is transferred to the nocking string 12 throughthe loading thread 47 and the primary lever 314, with a consequentincrease in the shooting force.

Said increase in the shooting force is in any case within the size ofthe archery tool itself, because the transfer of the force exerted bythe thrust increase springs 367, very high, occurs when the distance ofthe axis of the loading thread 47 almost coincides with the rotationaxis of the rotation pin 31, as described above with regard to the pin31, and this greatly reduces the resistant torque that must be overcomeby the torque achieved by the nocking string 12.

In said configuration, the torque which pushes the pre-load lever 381against the stop end element 390 is cancelled out, since the force issupported by the stem 345 and, consequently, the torque exerted by thereturn elastic element 387 no longer finds opposition.

The pre-load lever 381 then starts a clockwise rotation towards thestarting non-load arrangement.

In order to complete the rotation, the pre-load lever 381 must surpassthe vertical and this happens when the extra-stroke, indicated with “F”in FIG. 31 and FIG. 31A, of the stem 345 exceeds the distance accordingto the vertical direction, between the rotation centre of the secondtraction pin 386 in the end-of-stroke arrangement and the rotationcentre of the same second traction pin 386 when it is aligned with therotation centre of the first traction pin 385 and the pin 383 of thepre-load lever 381, said distance being indicated with “L” in FIG. 32and in FIG. 32A, and being detected along a direction parallel to saidstraight line of alignment of the rotation centres of the pins 386, 385and 383.

FIG. 46 shows a graph in which the draw in millimetres is indicated onthe abscissa and the force for achieving said draw expressed in Newtonson the ordinate; in said graph, a dashed line indicates a shooting curvein the absence of the pre-loadable external auxiliary accumulator 361,while a solid line indicates a shooting curve, in the loading step, inthe presence of the pre-loadable external auxiliary accumulator 361.

The pre-load tie rod 384, being flexible, adapts to said newconfiguration as shown in FIG. 33, where the pre-load lever 381 hascompleted the clockwise rotation.

By releasing the nocked arrow, the thrust increase springs 367, togetherwith the accompanying spring 368 when present, push the stem 345 towardsthe centre of the central body 11, so do also the springs of the thrustaccumulator 19; in this way, the energy received by the arrow is equalto that of the springs of the thrust accumulator 19 added to that of thethrust increase springs 367, and to that of the accompanying spring 368,or of the accompanying springs 368 if more than one are present.

FIG. 47 shows a graph in which the draw in millimetres is indicated onthe abscissa and the force for achieving said draw expressed in Newtonson the ordinate; in said graph, a dotted line indicates a return curvein the absence of the pre-loadable external auxiliary accumulator 361,while a solid line indicates a return curve in the presence of thepre-loadable external auxiliary accumulator 361.

FIG. 34 shows a variant embodiment of a pre-loadable external auxiliaryaccumulator 461 without the accompanying spring 368.

In this case, however, the trend of the shooting force may be unwelcometo the archer who, at the end of the draw, would have a peak load.

The advantage that is obtained by adding one or more accompanyingsprings 368 is that of avoiding an instantaneous overload to the nockingstring 12, and therefore to the user's hand, when the elastic returnelement 387 releases the thrust increase springs 367.

Both with the application of a pair of load increase devices 261, andwith the application of a pair of pre-loadable external auxiliaryaccumulators 361, an increase in the stored energy is obtained.

Furthermore, the ratio between stored elastic energy and maximumshooting force is approximately double the one currently declared by thecurrent technology, which allows increasing the performance with thesame effort for the archer or reducing the effort for the archer withthe same performance, facilitating, for example, the resistance inshooting competitions.

These solutions can be adopted in a performing way because at the end ofthe draw the lever arm that is formed between the axis of the loadingthread 47 and that of the rotation pin 31 is close to zero.Consequently, the force due to the deformation of the thrust increasesprings 267 and 367 can be very high and this entails a high storage ofenergy without there being an appreciable increase in the shootingeffort required to the archer. FIGS. 35 to 37 describe a variantembodiment of a thrust accumulator, indicated therein as a whole withthe number 419.

Like for the axial action thrust accumulators 19 and 20 described above,the thrust accumulator 419 comprises at least one compression loadspring, for example a plurality of Belleville springs 440, arranged inseries with each other, as clearly visible in FIG. 3.

Still in particular, in the present embodiment example, the thrustaccumulator 419 comprises two groups of load springs 440 and 441.

An axial action thrust accumulator 419 comprises at one end a fixed head443 and at the opposite end a movable head 444.

The axial action thrust accumulator 419 comprises a stem 445,translatable in the direction of its own axis X, to which the movablehead 444 is connected.

The stem 445 has a manoeuvring end 445 a, available for the connectionwith the loading means 21.

In particular, the stem 445 comprises, at the manoeuvring end 445 a, thefirst pulley 48 of the loading means 21.

In said particular variant embodiment, the thrust accumulator 419comprises a stroke adjustment system 492, configured to limit thecrushing of one or more springs, for example a group of springs 441.

Said technical solution, described for a thrust accumulator indicatedwith 419, is to be understood to be applicable also to the thrustaccumulators described above and indicated with 19 and 20.

Said stroke adjustment system 492 comprises a cup-shaped body 493,resting on the movable head 444 and free to translate therewith alongthe stem 445.

Said cup-shaped body 493 has a base 494 and a side wall 495 for limitingthe stroke.

Said side wall 495 has a variable height.

For example, this side wall 495 is connected to the base 494 by means ofa threaded connection 496.

The stroke adjustment system 492 also comprises an end-of-stroke disc497 arranged between the two groups of springs 440 and 441, which isconfigured to abut against the side wall 495 of the cup-shaped body 493causing the compression of the group of springs 441 contained in thecup-shaped body 493 to stop.

The springs 441, of which the stroke is to be limited, thus adjustingthe action of the same, are housed between the stem 445 and the sidewall 495.

In fact, in the crushing step of the springs 441, the side wall 495 ofthe stroke limiter rests on the end-of-stroke disc 497, preventing thesprings 441 themselves from being further crushed.

The height of the side wall 495, and therefore the stroke of the springs441, can be varied continuously.

FIG. 36 shows a thrust accumulator 419 with the side wall 495 alreadyarranged in contact with the end-of-stroke disc 497, in an arrangementwhich prevents the springs 441 from being crushed.

In FIG. 37 the side wall 495 is lowered and spaced from theend-of-stroke disc 497, in which case therefore a certain compression isallowed to the springs 441 until the side wall 495 abuts against theend-of-stroke disc 497.

Another stroke adjustment system 592 is shown in FIGS. 38 and 39, inrelation to a thrust accumulator 519.

In said stroke adjustment system 592, the side wall 595 of thecup-shaped body 593 is fixed to the base 594.

A calibrated shim 598 may be present inside the cup-shaped body 593, asclearly visible in FIG. 39.

By positioning or removing the calibrated shim 598, or by replacing acalibrated shim 598 with another calibrated shim with different height,the stroke and the degree of pre-compression of the springs of thethrust accumulator 519 are modified, with respect to the end-of-strokedisc 597.

FIGS. 40, 41, 41A and 41B show an archery tool 610 configured as acrossbow, it also to be understood as the object of the invention.

Said throwing tool 610 comprises a central body 611 from which a tiller611 a, a nocking string 612 for a dart and elastic energy storage meansoperated by the traction of the string 612 develop.

The peculiarity of the archery tool 610, of the crossbow type, accordingto the invention resides in the fact that the elastic energy storagemeans comprise:

-   -   two opposed primary levers 614 and 615 connected with respective        hinging means 616 to the central body 611; the nocking string        612 is constrained by its opposite ends 612 a and 612 b to        opposite free ends 617 and 618 of the primary levers 614 and        615;    -   an axial action thrust accumulator 619, defined on the tiller        611 a;    -   loading means 621 of said axial action thrust accumulator 619,        which loading means 621 are configured to induce a compression        in the thrust accumulator 619 following a traction of the        nocking string 612.

The thrust accumulator 619 is to be intended as the same or analogous toone of the thrust accumulators 19, 119, 419, 519 described above.

As described above for the archery tool 10, a frame 625 defining awindow is defined on the tiller 611 a, inside which window the thrustaccumulator 619 is placed.

Also the loading means 621 are to be intended as similar and equivalentto the loading means 21 described above, with a loading thread 647 and apulley system configured to cause a translation of the stem 645 of thethrust accumulator 619, as described above for the other variantembodiments of the invention.

The thrust accumulator 619 and the loading means 621 are mounted on thetiller 611 a.

Also in said embodiment of the invention, the hinging means 616comprise, for each primary lever 614 and 615, a pin 631, correspondingto the pin 31 described above, a notch 31 a being made on said pin 631for the passage of the loading thread 647.

In particular, in the present embodiment example, the pulley system,configured to cause a translation of the stem 645, comprises fourpulleys, a first pulley 648 pivoted to the manoeuvring end 645 a of thestem 645, a second pulley 649 pivoted to the tiller 611 a, and two thirdpulleys 649 a symmetrically pivoted to the central body 611 andconfigured to deflect the loading thread 647 from a respective primarylever 614 and 615 towards the thrust accumulator 619 mounted on thetiller 611 a.

In particular, in the present embodiment example of an archery tool 610configured as a crossbow, the loading thread 647 comprises a firstsection 647 a for the connection with the stem 645, and two secondsections 647 b for the connection with the respective primary levers 614and 615.

The first section 647 a and the second sections 647 b are connected insuch a way that the traction of a second section 647 b is transmitteddirectly to the first section 647 a.

In particular, the second sections 647 b are part of a single threadconnected to the first section 647 a by means of an eyelet 647 c , whicheyelet 647 c is crossed by the thread of the second sections 647 b.

In particular, the first section 647 a of the loading thread 647 isfixed at a first end to a fixed pin 650 integral with the tiller 611 a,while it features the eyelet 647 c at the second end.

Each of the second sections 647 b is constrained at a first end to acorresponding pin 651, in turn fixed to a corresponding primary lever614 or 615, and the other second section 647 b is connected to thesecond end.

In particular, as already described above, the two second sections 647 bare part of a single thread connected at its ends to the opposite pins651 of the primary levers 614 and 615.

Said embodiment for the archery tool 610 configured as a crossbow isobviously to be understood as a non-limiting example of the invention.

For example, in a not shown variant embodiment, the two second sections647 b of the loading thread 647 are connected to the first section 647 aby means of an intermediate slider block to which the corresponding endsof all said first section 647 a and second sections 647 b areconstrained.

The thrust accumulator 619 is intended as to be installable both in sucha way that, when the nocking string 612 is pulled, the springs of thethrust accumulator 619 are compressed in the direction going from thetiller 611 a towards the central body 611, as shown in the FIGS. 40, 41,41A and 41 B, and in such a way that the springs of the thrustaccumulator 619 are compressed in the direction going from the centralbody 611 to the tiller 611 a.

In both cases, it is possible to install a load increase device 261 asdescribed above on the tiller 611 a or a pre-loadable external auxiliaryaccumulator 361 as described above.

It has in practice been established that the invention achieves theintended task and objects.

In particular, with the invention a bow-type throwing tool has beendeveloped which is simpler and faster to calibrate and adjust withrespect to the bows of the known type.

Again in particular, with the present invention a bow-type throwing toolhas been developed which has the capability of transmitting to an arrowa much higher amount of energy than known devices already on the market.

Furthermore, with the invention a throwing tool has been developed withwhich a better let-off is achieved with respect to the bows of the knowntype.

In addition, a bow-type throwing tool which is structurally simpler andeasier to use has been developed with the invention.

The invention thus conceived is susceptible of numerous modificationsand variations, all of which are within the scope of the inventiveconcept; moreover, all the details may be replaced by other technicallyequivalent elements.

In practice, the materials used could be of any type, so long as theyare compatible with the specific use, as well as the contingent shapesand dimensions, according to requirements and the state of the art.

If the characteristics and techniques mentioned in any claim arefollowed by reference signs, these reference signs are to be intendedfor the sole purpose of increasing the intelligibility of the claimsand, consequently, such reference signs have no limiting effect on theinterpretation of each element identified by way of example from thesereference signs.

1. A bow-type throwing tool, comprising a central body, a nocking stringfor an arrow, and elastic energy storage means operated by the tractionof said string, said elastic energy storage means comprising: twoopposed primary levers connected with hinging means to said centralbody, said nocking string being constrained by its opposite ends toopposite free ends of said primary levers; two opposed axial actionthrust accumulators, defined on said central body; loading means of saidaxial action thrust accumulators configured to induce a compression insaid thrust accumulators following a traction of said nocking string,wherein said axial action thrust accumulator comprises at one end afixed head and at the opposite end a movable head, said axial actionthrust accumulator comprising a stem, translatable in the direction ofits own axis, to which said movable head is constrained, said loadingmeans comprising, for each thrust accumulator: a loading thread, whichis fixed at a first end to the central body and at the opposite secondend to a corresponding primary lever; a pulley system configured tocause a translation of said stem, along the line of said axis and in thecompression direction of a corresponding thrust accumulator, following atraction of said loading thread.
 2. The throwing tool according to claim1, wherein said hinging means comprise for each primary lever a pin, anotch being made on said pin for the passage of said loading thread,said notch being configured to allow the progressive reduction of thedistance between the axis of the loading thread and the rotation axis ofsaid pin during the traction step of the nocking string.
 3. The throwingtool according to claim 1, wherein the distance of the axis of theloading thread from the rotation axis of the pin is near zero, remaininggreater than zero.
 4. The throwing tool according to claim 1, whereinsaid pin, at said notch, has a solid part configured to define a curvedsurface for the rest of said loading thread, said curved surface havinga cusp, the distance between said cusp and the rotation axis of said pinbeing less than the radius of said loading thread.
 5. The throwing toolaccording claim 1, wherein said central body comprises hingingappendages.
 6. The throwing tool according to claim 1, wherein eachprimary lever comprises a free end and an opposite pivoting portion. 7.The throwing tool according to claim 1, wherein said central bodycomprises two opposite frames each defining a window, inside each ofwhich windows there is a corresponding thrust accumulator.
 8. Thethrowing tool according to claim 1, wherein each of said axial actionthrust accumulators comprises at least one compression load spring, saidaxial action thrust accumulator comprising, in particular, a pluralityof Belleville springs, arranged in series with each other.
 9. Thethrowing tool according to claim 1, wherein said thrust accumulatorcomprises a stroke adjustment system, configured to limit the crushingof one or more springs.
 10. The throwing tool according to claim 1,wherein said stem has a manoeuvring end, available for the connectionwith the loading means.
 11. The throwing tool according to claim 1,comprises a pair of load increase devices, configured to operate inseries with a corresponding thrust accumulator.
 12. The throwing toolaccording claim 1, wherein said load increase device comprises: a stemof the thrust accumulator, which is equipped with a striker head; acontainment box, fixed externally to the end of the frame; a slider bodyplaced so as to translate, along the thrust axis of the correspondingthrust accumulator, into a through hole defined at the end of the frameand into a coaxial guide hole defined in the containment box; aplurality of thrust increase springs, placed so as to act between acover of the containment box and a shoulder of the slider body; anabutment element, configured to abut against the striker head of thestem, said abutment element being configured to be able to adjust itsown axial position with respect to the slider body itself.
 13. Thethrowing tool according to claim 1, comprises a pair of pre-loadableexternal auxiliary accumulators configured to operate in series with acorresponding thrust accumulator.
 14. The throwing tool according toclaim 1, comprising: a stem of a corresponding thrust accumulator, whichis equipped with a striker head; a containment box, fixed externally tothe end of the frame; a first slider body placed so as to translate,along the thrust axis of the corresponding thrust accumulator, into athrough hole defined at the end of the frame); a second slider bodyplaced so as to translate, along the thrust axis, into a guide holedefined on the first slider body and into a coaxial guide hole definedin the containment box; a plurality of thrust increase springs, placedso as to act between a cover of the containment box and a first shoulderof the second slider body; one or more accompanying springs, placed soas to act between the shoulder of the second slider body and a facingsecond shoulder of the first slider body; a pre-load lever, pivoted to abracket developing from the cover through a pin; a pre-load tie rodconnected at a first end to a first traction pin fixed to the secondslider, and at the opposite second end to a second traction pin fixed tothe pre-load lever; an elastic return element constrained on one side tothe cover and on the opposite side to the pre-load lever.
 15. Thebow-type throwing tool configured as a crossbow, characterized in thatit comprisescomprising a central body from which a tiller , a nockingstring for a dart and elastic energy storage means operated by thetraction of the string develop, said elastic energy storage meanscomprising: two opposed primary levers connected with respective hingingmeans to said central body, said nocking string being constrained by itsopposite ends to opposite free ends of said primary levers an axialaction thrust accumulator, defined on said tiller; loading means of saidaxial action thrust accumulator, said loading means being configured toinduce a compression in the thrust accumulator following a traction ofsaid nocking string.
 16. A bow-type throwing tool, comprising a centralbody, a nocking string for an arrow, and elastic energy storage meansoperated by the traction of said string, said elastic energy storagemeans comprising: two opposed primary levers connected with hingingmeans to said central body, said nocking string being constrained by itsopposite ends to opposite free ends of said primary levers; two opposedaxial action thrust accumulators, defined on said central body; loadingmeans of said axial action thrust accumulators configured to induce acompression in said thrust accumulators following a traction of saidnocking string.
 17. Hinging means for a bow-type throwing tool, saidbow-type throwing tool comprising a central body, a nocking string foran arrow, and elastic energy storage means operated by the traction ofsaid string, said elastic energy storage means comprising two opposedprimary levers connected with said hinging means to said central body,said hinging means comprising, for each primary lever, a pin, a notchbeing made on said pin for the passage of a loading thread, said notchbeing configured to allow the progressive reduction of the distancebetween the axis of said loading thread and the rotation axis of saidpin during the traction step of the nocking string.
 18. The hingingmeans according claim 17, wherein the distance of the axis of theloading thread from the rotation axis of the pin is near zero, remaininggreater than zero.
 19. The hinging means according to claim 17, whereinthe distance between the cusp and the rotation axis of the pin is lessthan the radius of the loading thread.
 20. The hinging means accordingto claim 17, wherein said notch is shaped in such a way that the axis ofthe loading thread stops at a distance from the axis of the pin whichcan be comprised between 1 and 5 hundredths of a millimeter, whereinsaid distance between the axis of the pin and the axis of the loadingthread corresponds to the difference between the radius of the loadingthread and the distance between the cusp and the axis of the pin.
 21. Apin for bow-type throwing tools, wherein a notch is made on said pin forthe passage of a loading thread, said notch being configured to allowthe progressive reduction of a distance between an axis of said loadingthread and a rotation axis of said pin.
 22. The pin according to claim21, wherein at the notch, it has a solid part configured to define acurved surface for the rest of the loading thread.
 23. The pin accordingto claim 21, wherein the notch is concave and the solid part of the pinis correspondingly convex.
 24. The pin according to claim 22, whereinthe curved surface has a cusp.
 25. The pin according to claim 22,wherein the axis of the pin crosses the pin at the notch, and not at thesolid part.
 26. The pin according to claim 21, wherein said notchdevelops like an arc of a circle over an angle comprised between 180°and 200°.
 27. A load increase devices, configured to operate in serieswith a corresponding thrust accumulator, said load increase devicecomprising: a stem of the thrust accumulator, which is equipped with astriker head, a containment box, fixed externally to the end of a frame,a slider body placed so as to translate, along the thrust axis of thecorresponding thrust accumulator, into a through hole defined at the endof the frame and into a coaxial guide hole defined in the containmentbox, a plurality of thrust increase springs, placed so as to act betweena cover of the containment box and a shoulder of the slider body. 28.The load increase devices according to claim 27, wherein said sliderbody also comprises an abutment element, configured to abut against thestriker head of the stem, said abutment element being configured to beable to adjust the axial position with respect to the slider bodyitself, with the aim of defining the distance with the striker head. 29.A pre-loadable external auxiliary accumulator comprising: a stem of athrust accumulator which is equipped with a striker head; a containmentbox, fixed externally to the end of a frame; a first slider body placedso as to translate, along a thrust axis of the corresponding thrustaccumulator, into a through hole defined at the end of the frame; asecond slider body placed so as to translate, along the thrust axis,into a guide hole defined on the first slider body and into a coaxialguide hole defined in the containment box; a plurality of thrustincrease springs, placed so as to act between a cover of the containmentbox and a first shoulder of the second slider body; a pre-load lever,pivoted to a bracket, developing from the cover, through a pin; apre-load tie rod constrained at a first end to a first traction pinfixed to the second slider, and at the opposite second end to a secondtraction pin fixed to the pre-load lever; an elastic return elementconstrained on one side to the cover and on the opposite side to thepre-load lever.
 30. The pre-loadable external auxiliary accumulatoraccording to claim 29, further comprising: one or more accompanyingsprings, placed so as to act between the first shoulder of the secondslider body and a facing second shoulder of the first slider body; astroke adjustment system for said accompanying springs, defined below byway of example by the striker perimeter wall.